Prepare the filling in the slow cooker as instructed.
Preheat the oven to 425 degrees F.
Roll out the bottom pie crust: Remove one pie dough from the fridge and place it on a lightly floured surface. Roll the dough into a 12-inch circle and transfer it to a 9-inch pie dish.
Fill the pie: Add the cooled chicken pot pie filling to the prepared pie crust.
Roll out the second pie crust and place it over the filling. Seal the edges of the crusts together and crimp them for a decorative finish. Make small slits in the top crust to allow steam to escape.
In a small bowl, whisk together 1 egg and 1 tablespoon of milk. Brush this egg wash over the top crust.
Bake the pie in the preheated oven for 40-50 minutes, or until the crust is golden brown and the filling is bubbly.
Allow the chicken pot pie to cool for 15-20 minutes before serving to allow it to set up.